EWS - Problem connecting to mailbox.

EWS - Problem connecting to mailbox.

Hi ALL.
I have SDP11.1 Build 11122  + Exchange 2016. Several days ago i detect some mail fetch issue.
I check all settings and have this message:
E-mail settings saved successfully.
But error occurred while trying to check connection with mail server - Problem connecting to mailbox.

 Where i can find more info about connection problem?

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